All Ears: Innovation and Adoption in Hearing Aids

Introduction

Hearing aids have evolved from simple mechanical devices into sophisticated wearable computers incorporating wireless connectivity, artificial intelligence and advanced acoustic processing. A closer look at the development of hearing aids offers insight into the relationship between technology, adoption and intellectual property.

Historical Hearing Aids

Many UK manufacturers of nineteenth-century hearing aids obtained patents for their inventions, such as Alphonsus William Webster’s “Apparatus to assist the organ of hearing.” To drive sales, products such as James Yearsley’s “Artificial Tympanum” were marketed as patented despite only being protected by a provisional patent. Others marketed themselves as “patentees,” such as F. C. Rein & Son, justified to the extent that at least some of their products were patented. 

Today, false representation of a product as patented may constitute an offence under Section 110 of the UK Patents Act, 1977. In the nineteenth century, however, some manufacturers exploited the patent system to afford their products scientific credibility. Although technology has advanced significantly, many of the intellectual property issues faced by nineteenth-century manufacturers remain recognisable today.

Acoustic Processing

Perhaps the most important aspect of hearing aid technology is acoustic processing. Modern devices are designed to enable clearer speech perception and suppress distracting background noise to reduce listening fatigue.

Just as listeners may turn their ear towards a speaker, directional microphones can be used to improve speech understanding. Directional microphones may be fixed or adaptive, focusing on the main sound in the environment. The direction of a sound may be determined based on the delay between sound arriving at a front and rear microphone. Beamforming reduces the sensitivity of the microphone to unwanted noise sources, for example behind the listener.

Artificial intelligence also finds a place in hearing aid technology. Founded by a mechanical engineer with experience in ultrasound machines, AI startup Fortell recently closed a funding round having raised $163 million. Using artificial intelligence to precisely differentiate between speech and background noise, Fortell claims that its hearing aids eliminate 98% of background noise.

Improvements in acoustic processing remain the most significant driver of modern hearing-aid performance, evidenced by continued research and investment in the sector.

Battery Power

Recent UK sales figures suggest that rechargeable hearing aids are gaining prominence over those with replaceable batteries. In the UK, around 600 million zinc-air batteries are sent to landfill each year. Rechargeable lithium-ion batteries are used in the majority of consumer electronics such as smartphones, laptops, and now, hearing aids.

Silver-zinc batteries were previously developed by NASA for space applications and present a number of advantages over both lithium-ion and zinc-air batteries. Silver-zinc batteries are rechargeable, largely recyclable, and employ a water-based chemistry, making them non-flammable. If necessary, a silver-zinc battery can be replaced with a traditional zinc-air battery, for example if a hearing aid runs out of charge when the wearer is away from home.

Battery size also impacts the overall footprint of the hearing aid. Receiver-in-Canal hearing aids are small and lightweight, with a two-part design connected by a thin wire. The receiver is housed within the ear canal, which can reduce distortion compared to Behind-the-Ear systems. With the battery housed behind the ear, battery life is extended compared to Completely-in-Canal hearing aids.

As hearing aids incorporate more connectivity and processing features, advances in battery technology will remain essential to balancing functionality, size and wearability.

Connectivity

In 1867, Frederick Charles Rein obtained a patent for incorporating tubing into church pews to transmit sermons to churchgoers. In 2026, modern hearing-assistive technology is being implemented in communal spaces to improve accessibility. At Vue cinemas in the UK, around 200 cinema screens have been fitted with Auri Auracast™ listening systems, which can also be used to deliver audio description. The system has also been introduced in Brighton railway station and Frankfurt airport. Auracast™ features have even been implemented in Windows 11.

Auracast™ is a feature of Bluetooth® Low Energy (LE) Audio, which enables simultaneous streaming to multiple receivers without requiring one-to-one device pairing. Users up to around 100 metres from the transmitter can choose to join the stream, similar to choosing a WiFi network. The system uses the LC3 audio compression codec to reduce latency, which is particularly important for video streams and live speakers.

While many of the standards associated with Auracast™ are open and royalty-free, innovators are already seeking to patent systems implementing Auracast™ features, often focused on efficient switching between streams. Connectivity is increasingly transforming hearing aids from standalone medical devices into integrated components of a wider digital ecosystem.

Designs in Hearing Aids

While users report that stigma still exists surrounding the appearance of hearing aids, sales are increasing in the UK, showing an encouraging trend towards adoption of this important assistive technology. Hearing aids are available in a variety of shapes, sizes, and colours, many of which are protected by design rights in the UK and beyond. In the UK, design registration protects “the appearance of the whole or a part of a product” (S1(2) RDA 1949). 

Features of a product which “must fit” another are excluded from protection in a registered design (S1C(2) RDA 1949). A similar exclusion applies for UK (unregistered) design right, in that “design right does not subsist in... features of shape or configuration of an article which... enable the article to be connected to, or placed in, around or against, another article so that either article may perform its function...” (S213(3)(b)(i) CDPA 1988).

In Ocular Sciences v Aspect Vision Care Ltd (1997), which dealt with an unregistered design right, it was decided that the “must fit” exclusion applies even when a product is shaped to fit a body part – in this case, an eyeball. Justice Laddie saw no reason the word “article” should be interpreted narrowly “so as to exclude living or formerly living things.” Based on the current case law, it follows that unregistered design right in the UK cannot protect aspects of a hearing aid dictated by the shape of the outer ear or ear canal. Manufacturers therefore often seek registered design protection for features that are not dictated solely by functional fit requirements.

Many aspects of the appearance can be protected by registered designs. Innovative examples extend from unobtrusive hearing aid glasses to intricate hearing aid jewellery, while slimline and miniature models resemble wireless earbuds. As the hearing aid market grows, more designs become available, appealing to wider demographics and enabling wearers to choose a style that is right for them.

Before the European Boards of Appeal

The European Boards of Appeal have heard several cases involving major hearing aid manufacturers in recent years. In all four cases below, the Boards showed a willingness to revoke hearing aid patents for lack of inventive step, where the alleged advantages were obvious or not achieved across the entire scope of the claims.

In T 1924/20, the patent related to an encapsulated hearing device designed to remain in the ear canal for weeks or months. The Board found two novel features over the prior art: the battery was hardwired to the electronics module; and the hull was formed by thermoforming. However, the Board deemed these features to be unrelated and could not be considered together when evaluating inventive step.

T 1962/23 relates to a system for manufacturing hearing aids, with controlled security access for personalising the hearing aid settings. The Board found that the claimed system included a handful of features related to security credentials and access rights which were not disclosed by the prior art. However, those features were found to lack a technical contribution, and no credible technical security effect was demonstrated.

In T 0094/24, a patent to a hearing aid with a flexible carrier antenna was revoked for lack of inventive step. The hearing aid contained an indentation in the circuit board intended to accommodate the antenna terminal. However, the Board concluded that the claim was drafted very broadly, covering embodiments wherein the indentation did not reduce the size of the hearing aid. Therefore, the patent did not credibly achieve a technical effect.

A patent to an assembly for a hearing aid was revoked in T 1155/24, as the Board viewed the claimed invention as a combination of unrelated technical features. Applying known antenna techniques to a hearing aid assembly was not sufficient to demonstrate a synergistic technical effect.

As demonstrated in the cases above, the hearing aid industry is heavily litigated in Europe, with leading manufacturers regularly challenging each other’s patents and testing the boundaries of what constitutes a genuine technical contribution.

Conclusion

Sophisticated hearing aid technologies such as AI-enabled acoustic processing and multi-device streaming are being developed with the goal of improving communication for people with hearing loss. However, throughout the history of hearing aids, intellectual property has also played an important role in encouraging innovation. As hearing aids become even more advanced, intellectual property will be central to the future development of the industry.

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